In oil and gas fields, the extraction of hydrocarbon fluids, such as oil and natural gas, is typically handled through a system of pipelines that transport collected fluids containing the hydrocarbon fluids from the mouth of each well, to a production facility. At the production facility, the collected fluids are processed in order to separate the oil, gas, water and solid sediment, and to prepare the various fluids for export and/or storage.
The collection pipelines from each well in the field are interconnected at a wellhead containing an array of valves. The valves control the flow of collected fluids to a general production line for the process of separation and measurement of the total flow, and, selectively, to a measurement line which deviates the production of each well separately for periodic measurement of the parameters that indicate the operating conditions at each well. These parameters can then be utilized in determining the optimal manner in which to operate each well to maximize production. Typically, such measurement is performed well-by-well such that the flow of fluid from a single well is diverted for measurement while the flow of fluid from all other wells in the oil field are kept aligned towards the head of production.
In both flows (the flow to the measurement head and the flow to the production head), instruments are positioned to measure the pressures and volumes of oil, gas and water handled. The instruments may include pressure gauges, orifice plates and/or other basic measuring instruments known in the art. With existing systems, the valves in the wellhead are controlled manually by personnel at the production facility, in order to divert and route the flow of collected fluid from each well, as desired. After separation, oil is pumped to a central storage station, for the appropriate storage and/or recompression, as needed.
As will be readily appreciated, and even in the case where multiple wells are obtaining fluid from the same underground reservoir, the flow and pressure of each individual well and associated pipeline is dependent upon a variety of factors. For example, alterations in the downhole vicinity of each individual well, as well as any repairs made to each well space, may affect the flow and pressure of a well. In addition, the diameter of the pipelines carrying the collected fluid, which may decrease over time due to the buildup of limescale deposits or other products formed during the production phase of the well, as well as friction losses along the different lengths of discharge lines of each well, may also affect the flow and pressure of each well. As a result, the pressures on arrival at the wellhead may be different for each well, despite being potentially sourced from the same reservoir.
As will be appreciated, wells exhibiting a higher pressure at the wellhead tend to limit or impede the contribution of wells exhibiting lower pressures. That is, the flow of wells exhibiting higher pressures arriving at the wellhead generates a backpressure against the lower pressure wells, thus impeding the flow of the lower-pressure wells and lowering their associated production.
Particularly in mature fields or fields exhibiting rapidly declining production, such backpressures can cause significant disparities in the production rates of each individual well. These disparities often go unrecognized, however, because production of the wellhead is typically viewed as a whole. In any event, the overall production levels for the field suffers because lower pressure wells typically will have much lower production rates than would be possible if the undesirable backpressures were absent or significantly reduced.
Accordingly, there is a need for a system and method to reduce or optimize backpressures between different wells within an oil/natural gas field, to enhance the production levels of the individual wells and, thus, the field as a whole.